The point is that the story in the song was not the only time that the "lights went out in Georgia" for innocent men.
I could go on a little more, but Dancing with the Stars and NCIS are both on and I have to focus to switch back and forth and follow them.
Except that the song says "That's THE night the lights went out in Georgia," not "That's ONE OF the nights..." Also, the chorus makes clear that it's a "Backwoods southern lawyer" who is the one to blame, not Sherman or even yankees in general. But, if your position is that any story about anything bad ever happening in the south at any time is actually a metaphor for Sherman's march, then I guess I'll just leave you to continue stewing in your 140 year old juices.
Do you want to take a whack at "The Devil Went Down to Georgia" by explaining how Sherman challenged someone to a fiddling match?